My question involves criminal law for the state of: Missouri

I live in a small town in the middle of Missouri with what many consider a corrupt police force. Last week to show my disapproval for the the P.D. I gave 2 officers the finger while in a drive thru line. They came over to the car, told my friend who was driving to pull over and get out of line. They told me to get out and give them my I.D., I complied. I was then arrested and charged with Disorderly Conduct and taken to jail where I was held for a full 24 hours.*

This is the exact law I'm being charged with.*Sec. 18-84. - Disorderly conduct.(a)It shall be unlawful for any person to be guilty of disorderly conduct or of any conduct tending toward a breach of the peace. The causing or making of any unnecessary loud noise or shouting or yelling shall be considered disorderly conduct.(b)It shall be unlawful for any person to engage in any violent, tumultuous, offensive or disorderly conduct; by threatening, traducing, quarreling, challenging to fight or fighting; or by using obscene, offensive, profane or unseemly language to the annoyance, disturbance or vexation of another.

I've been doing a good amount of research regarding the finger and its 1st amendment protection. There are plenty of examples of high courts (including the SCOTUS) overturning convictions and ruling that speech (including gestures) insulting LEOs and other government officials is completely protected. I may have technically broke that law but if that's the case than the law itself is illegal.*

I've gone to the station to get the police report but it won't be ready for a few more days, I'm waiting on it before I make my next move. I'm strongly considering filing a complaint with the ACLU ( and maybe a lawsuit against the P.D.), they've successfully defended cases very similar to mine. More immediately though I need a lawyer, but I barely have enough money to pay my bills let alone a lawyer or even a fine if convicted. My first court date is in about a month and a half, will I be able to get *a public defender then?

This is my first arrest in my life so I don't really know what to expect, the clean record will be a help though.

*How can I ask to have the charges dropped? Paper work? Go directly to the court and try to talk to the attorney's office? Or do I have to wait and ask the judge to dismiss the case?

Any advise on this situation is really appreciated, I know I've missed some questions so please talk about things I can do that I've missed.*

P.S. this was after midnight so not to many people were around who could've been offended (even though that's not against the law) or who's peace would've been disturbed by a silent gesture.

*P.P.S. the finger wasn't accompanied by anything that could've been perceived as a threat of violence and while being arrested I was not resisting, I was completely submissive.*